粘滑过程中声发射序列的时间分布及前兆特征

TIME SEQUENCES OF ACOUSTIC AEMISION IN STICK-SLIP PROCESS AND THEIR FORECASTING SIGNIFERENCE

用声发射波形采集分析系统记录的完整花岗岩在固体围压下破裂及粘滑过程中产生的声发射波形,研究了声发射和粘滑时间序列与天然地震序列的关系,讨论了粘滑过程的时间分布,发现粘滑事件的累积频度曲线随时间的变化受围压和应变率影响,大致呈现指数函数和线性关系两种形式。总事件(包括粘滑和声发射)的累积频度随时间的变化在不同的实验条件下呈现出对数函数形式,粘滑序列中的声发射随时间减少。本文的结果对于研究不同应变速率及不同震源深度的地区的地震活动时间分布特征,以及在判别地震活跃期内不同阶段强震序列类型和前兆特征有一定参考作用。

The waveform of acoustic emission during fracture and stick slip process in intactgranite sample under solid confining presure were recorded by the ACOUSTIC EMISIONWAVE GATHERING AND ANALYSISING SYSTEM, the relations between acoustic e-mission, stick-slip sequence and natural seismic sequence were contrasted in this paper.It shows that confining and strain rate have a great influence upon the change in accumu-lated frequence of stick-slip events with time, and it can be represented by an exponentfunction or linear function. The change in accumulated frequence of total events (includedstick-slip and acoustic emission) with time can be represented by logarithm function un-der different experimental conditions. The number of acoustic emission events during stick-slip process decreases with time. The above results may be useful for studing time sequence of seismicity in some re-gions with different strain rate and focal deeps and dishtinguishing sequence type or pre-cursor feature of strong earthquake to occur in different stages of seismic periods.